1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method.
2. Description of the Related Art
Since digital techniques today are extensively employed in photocopying machines, many of them perform multi-functions including not only a copying function but also other additional functions. Some photocopying machines work as a printer, a facsimile machine and even a filing machine. They may read and print filed data and file an image coming from a facsimile service.
Such advanced digital photocopying machines are widely accepted because a user can fax or file a document by simply placing the document on an automatic document feeder in the same way as he or she copies the document.
The digital photocopying machine is improved in its copying rate year by year and today reaches a rate of 20 to 80 sheets/minute. For this speed performance, many users prefer a digital photocopying machine rather than a conventional dedicated photocopying machine with a slow operational speed when many documents need copying, faxing or filing. The user needs to wait on standby in front of a machine to process a large quantity of documents until all documents are read, or the user needs to return to the machine to retrieve the documents when they are all processed.
When a large quantity of documents are processed, the orientation of all documents is not always aligned. Thus, the user needs to first align the orientation of the documents.
The operation of aligning the orientation of a plurality of documents before copying or faxing them on the digital photocopying machine is a troublesome job. Especially when the documents are of a sheet size A, handling them is easy if they are all in a portrait format. However, if portrait and landscape (A4R) formats are mixed, the alignment operation is open to two options of rightward alignment or leftward alignment. Although the A4 documents are typically loaded in a portrait alignment in a feeder in the photocopying machine, they are occasionally placed in a landscape alignment. The A4R (landscape aligned) documents are placed with their text aligned in a normal direction or in an inverted direction facing the port of the feeder. When holes are drilled on one margin of each document for binding purposes, the documents may be intentionally placed left side right.
FIG. 1 shows document orientations 102-109 when standard A4-size original documents are set in an automatic document feeder 101. As shown, a diversity of alignment settings are possible.
Because of a diversity of document settings, the alignment method of documents is also different from user to user.
With the documents not aligned, the photocopying machine delivers copy sheets having a diversity of alignments. If the number of copies increases, the user has to carry out a very tedious job for alignment. Some photocopying machines features an automatic stapling function. With the automatic stapling function enabled, the resulting copy sheets aligned in a diversity of directions are stapled as is.
Today, a reduction layout process today is available in which a plurality of documents are sequentially read, the read images are reduced, and the reduced images are laid out and printed on a single paper sheet.
When the documents are different in alignment, the alignment of the images of the documents, if subjected to the reduction layout process, are not consistent, and the resulting images are aesthetically unacceptable.
Document orientation determination techniques have been developed to free the user from an alignment operation of the documents and to rectify the difference in the setting of the documents from user to user. By integrating a sensor technique for sensing the orientation of the documents fed into a digital photocopying machine, the user is freed from the tedious job of aligning the documents.
Typically available as orientation determination techniques are a method of using a character recognition technique and a method of using a layout recognition technique. These techniques quickly perform the orientation determination process by checking part of the written content in an original document and outputting the result. In the method of using the character recognition technique, a text area of the original document is extracted, and characters in the text area are determined for the correction orientation.
The document orientation determination technique recognizes the feature of the text in the original document to recognize the orientation of the original document, and its performance level is not very high. The document orientation determination technique is subject to error. Since color documentation finds widespread use today, the document orientation determination technique has to work as well in color documentation.
Since the document orientation determination technique is conventionally used for black-and-white documents, an image is handled as a binary image of white and black levels in the document orientation determination process.
Many digital multi-purpose photocopying machines today, even if they are used for a black-and-white copying, incorporate a color CCD to read color images, since the function as a scanner is also important.
Since the orientation determination function is designed to work in the black-and-white original documents, color information, though available from the color CCD, remains unused in the orientation determination process. For this reason, the orientation determination occasionally fails to function properly on original documents.
(1) When the image of a two-color or three-color document, which is in widespread use today, is input with its text area blurred, the orientation of the document is not correctly determined, depending on the color, when its text area is blurred.
(2) The color text area most important in the determination of the orientation occasionally falls outside the area of interest in the orientation determination process.
(3) When a document with its text in one color and with its background in another color is handled, the orientation determination process fails to work properly.